When GMs blunder

Found this beauty in my "Chess Tactics for Beginners" CD that I received yesterday. Made me feel better about the times where I drop a major piece.

[Event "URS-ch49"]
[Site "Frunze"]
[Date "1981.12.??"]
[Round "6"]
[White "Mikhalchishin, Adrian"]
[Black "Romanishin, Oleg M"]
[Result "0-1"]
[ECO "D85"]
[WhiteElo "2535"]
[BlackElo "2590"]
[PlyCount "24"]
[EventDate "1981.11.??"]
[EventType "tourn"]
[EventRounds "17"]
[EventCountry "URS"]
[EventCategory "12"]
[Source "ChessBase"]

1. d4 Nf6 2. c4 g6 3. Nf3 Bg7 4. Nc3 d5 5. cxd5 Nxd5 6. e4 Nxc3 7. bxc3 c5 8. Be3 Qa5 9. Qd2 Nc6 10. Rb1 cxd4 11. cxd4 O-O 12. d5 Bc3 0-1

UPDATE
Fun fact. Three years earlier, Mikhalchishin had beaten a young Kasparov in tournament play.